TLR4 knockout can improve dysfunction of β-cell by rebalancing proteomics disorders in pancreas of obese rats

Effect of Akkermansia muciniphila on pancreatic islet β-cell function in rats with prediabetes mellitus induced by a high-fat diet

Prediabetes is an important stage in the development of diabetes. It is necessary to find a safe, effective and sustainable way to delay and reverse the progression of prediabetes. Akkermansia muciniphila (A. muciniphila) is one of the key bacteria associated with glucose metabolism. Recent studies mainly focus on the effect of A. muciniphila on obesity and insulin resistance, but there is no research on the effect of A. muciniphila on pancreatic β-cell function and its mechanism in prediabetes. In this study, we investigated the effects of A. muciniphila on β-cell function, apoptosis and differentiation, as well as its effects on the gut microbiome, intestinal barrier, metaflammation and the expression of Toll-like receptors (TLRs) in a high-fat diet (HFD)-induced prediabetic rat model. The effect of A. muciniphila was compared with dietary intervention. The results showed both A. muciniphila treatment and dietary intervention can reduce metaflammation by repairing the intestinal barrier in rats with prediabetes induced by an HFD and improve β-cell secretory function, apoptosis and differentiation through signaling pathways mediated by TLR2 and TLR4. Additionally, A. muciniphila can further elevate β-cell secretion, attenuate apoptosis and improve differentiation and the TLR signaling pathway on the basis of diet.

Identification of Lipotoxicity-Related Biomarkers in Diabetic Nephropathy Based on Bioinformatic Analysis

Objective: This study is aimed at investigating diagnostic biomarkers associated with lipotoxicity and the molecular mechanisms underlying diabetic nephropathy (DN). Methods: The GSE96804 dataset from the Gene Expression Omnibus (GEO) database was utilized to identify differentially expressed genes (DEGs) in DN patients. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted using the DEGs. A protein-protein interaction (PPI) network was established to identify key genes linked to lipotoxicity in DN. Immune infiltration analysis was employed to identify immune cells with differential expression in DN and to assess the correlation between these immune cells and lipotoxicity-related hub genes. The findings were validated using the external dataset GSE104954. ROC analysis was performed to assess the diagnostic performance of the hub genes. The Gene set enrichment analysis (GSEA) enrichment method was utilized to analyze the key genes associated with lipotoxicity as mentioned above. Result: In this study, a total of 544 DEGs were identified. Among them, extracellular matrix (ECM), fatty acid metabolism, AGE-RAGE, and PI3K-Akt signaling pathways were significantly enriched. Combining the PPI network and lipotoxicity-related genes (LRGS), LUM and ALB were identified as lipotoxicity-related diagnostic biomarkers for DN. ROC analysis showed that the AUC values for LUM and ALB were 0.882 and 0.885, respectively. The AUC values for LUM and ALB validated in external datasets were 0.98 and 0.82, respectively. Immune infiltration analysis revealed significant changes in various immune cells during disease progression. Macrophages M2, mast cells activated, and neutrophils were significantly associated with all lipotoxicity-related hub genes. These key genes were enriched in fatty acid metabolism and extracellular matrix-related pathways. Conclusion: The identified lipotoxicity-related hub genes provide a deeper understanding of the development mechanisms of DN, potentially offering new theoretical foundations for the development of diagnostic biomarkers and therapeutic targets related to lipotoxicity in DN.

Fatty acids and inflammatory stimuli induce expression of long-chain acyl-CoA synthetase 1 to promote lipid remodeling in diabetic kidney disease

Fatty acid handling and complex lipid synthesis are altered in the kidney cortex of diabetic patients. We recently showed that inhibition of the renin-angiotensin system without changes in glycemia can reverse diabetic kidney disease (DKD) and restore the lipid metabolic network in the kidney cortex of diabetic (db/db) mice, raising the possibility that lipid remodeling may play a central role in DKD. However, the roles of specific enzymes involved in lipid remodeling in DKD have not been elucidated. In the present study, we used this diabetic mouse model and a proximal tubule epithelial cell line (HK2) to investigate the potential relationship between long-chain acyl-CoA synthetase 1 (ACSL1) and lipid metabolism in response to fatty acid exposure and inflammatory signals. We found ACSL1 expression was significantly increased in the kidney cortex of db/db mice, and exposure to palmitate or tumor necrosis factor-α significantly increased Acsl1 mRNA expression in HK-2 cells. In addition, palmitate treatment significantly increased the levels of long-chain acylcarnitines and fatty acyl CoAs in HK2 cells, and these increases were abolished in HK2 cell lines with specific deletion of Acsl1(Acsl1KO cells), suggesting a key role for ACSL1 in fatty acid β-oxidation. In contrast, tumor necrosis factor-α treatment significantly increased the levels of short-chain acylcarnitines and long-chain fatty acyl CoAs in HK2 cells but not in Acsl1KO cells, consistent with fatty acid channeling to complex lipids. Taken together, our data demonstrate a key role for ACSL1 in regulating lipid metabolism, fatty acid partitioning, and inflammation.

Analysis of the management and therapeutic performance of diabetes mellitus employing special target

Diabetes mellitus (DM) is a chronic metabolic condition characterized predominantly by hyperglycemia. The most common causes contributing to the pathophysiology of diabetes are insufficient insulin secretion, resistance to insulin's tissue-acting effects, or a combination of both. Over the last 30 years, the global prevalence of diabetes increased from 4% to 6.4%. If no better treatment or cure is found, this amount might climb to 430 million in the coming years. The major factors of the disease's deterioration include age, obesity, and a sedentary lifestyle. Finding new therapies to manage diabetes safely and effectively without jeopardizing patient compliance has always been essential. Among the medications available to manage DM on this journey are glucagon-like peptide-1 agonists, thiazolidinediones, sulphonyl urease, glinides, biguanides, and insulin-targeting receptors discovered more than 10 years ago. Despite the extensive preliminary studies, a few clinical observations suggest this process is still in its early stages. The present review focuses on targets that contribute to insulin regulation and may be employed as targets in treating diabetes since they may be more efficient and secure than current and traditional treatments.

Type I Diabetes Pathoetiology and Pathophysiology: Roles of the Gut Microbiome, Pancreatic Cellular Interactions, and the 'Bystander' Activation of Memory CD8+ T Cells

Type 1 diabetes mellitus (T1DM) arises from the failure of pancreatic β-cells to produce adequate insulin, usually as a consequence of extensive pancreatic β-cell destruction. T1DM is classed as an immune-mediated condition. However, the processes that drive pancreatic β-cell apoptosis remain to be determined, resulting in a failure to prevent ongoing cellular destruction. Alteration in mitochondrial function is clearly the major pathophysiological process underpinning pancreatic β-cell loss in T1DM. As with many medical conditions, there is a growing interest in T1DM as to the role of the gut microbiome, including the interactions of gut bacteria with Candida albicans fungal infection. Gut dysbiosis and gut permeability are intimately associated with raised levels of circulating lipopolysaccharide and suppressed butyrate levels, which can act to dysregulate immune responses and systemic mitochondrial function. This manuscript reviews broad bodies of data on T1DM pathophysiology, highlighting the importance of alterations in the mitochondrial melatonergic pathway of pancreatic β-cells in driving mitochondrial dysfunction. The suppression of mitochondrial melatonin makes pancreatic β-cells susceptible to oxidative stress and dysfunctional mitophagy, partly mediated by the loss of melatonin's induction of PTEN-induced kinase 1 (PINK1), thereby suppressing mitophagy and increasing autoimmune associated major histocompatibility complex (MHC)-1. The immediate precursor to melatonin, N-acetylserotonin (NAS), is a brain-derived neurotrophic factor (BDNF) mimic, via the activation of the BDNF receptor, TrkB. As both the full-length and truncated TrkB play powerful roles in pancreatic β-cell function and survival, NAS is another important aspect of the melatonergic pathway relevant to pancreatic β-cell destruction in T1DM. The incorporation of the mitochondrial melatonergic pathway in T1DM pathophysiology integrates wide bodies of previously disparate data on pancreatic intercellular processes. The suppression of Akkermansia muciniphila, Lactobacillus johnsonii, butyrate, and the shikimate pathway-including by bacteriophages-contributes to not only pancreatic β-cell apoptosis, but also to the bystander activation of CD8⁺ T cells, which increases their effector function and prevents their deselection in the thymus. The gut microbiome is therefore a significant determinant of the mitochondrial dysfunction driving pancreatic β-cell loss as well as 'autoimmune' effects derived from cytotoxic CD8⁺ T cells. This has significant future research and treatment implications.

TLR4 inhibition ameliorated glucolipotoxicity-induced differentiation suppression in osteoblasts via RIAM regulation of NF-κB nuclear translocation

TLR4 is a key innate immune signal that mediates glucolipid toxicity through yet unclear mechanisms. Here, TLR4 truncation ameliorated bone metabolism disorders in diabetic rats, and the underlying mechanisms were explored by proteomics. Our study showed that TLR4 truncation inhibited bone loss induced by diabetes in rats. In addition, a proteomic analysis screen exposed the differential proteins associated with immune reactivity and T cell activation (RIAM and Class II histocompatibility antigen, M β1 chain). Further cellular experiments showed that TLR4 mediated the inhibition of osteoblast differentiation induced by glucolipotoxicity and promoted an increase in the nuclear level of RIAM-NF-κB. Mechanistic studies showed that TLR4 mediated glucolipotoxicity induced damage in bone metabolism primarily by regulating RIAM-NF-κB interactions, which promoted RIAM-NF-κB nuclear translocation. In conclusion, we confirmed that TLR4 inhibition could delay bone metabolism disorders induced by glycolipid toxicity via RIAM regulation of NF-κB nuclear translocation.

Mucin1 relieves acute lung injury by inhibiting inflammation and oxidative stress

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is a kind of diffuse inflammatory injury caused by various factors, characterized by respiratory distress and progressive hypoxemia. It is a common clinical critical illness. The aim of this study was to investigate the effect and mechanism of the Mucin1 (MUC1) gene and its recombinant protein on lipopolysaccharide (LPS)-induced ALI/ARDS. We cultured human alveolar epithelial cell line (BEAS-2B) and used MUC1 overexpression lentivirus to detect the effect of MUC1 gene on BEAS-2B cells. In addition, we used LPS to induce ALI/ARDS in C57/BL6 mice and use hematoxylin and eosin (H&E) staining to verify the effect of their modeling. Recombinant MUC1 protein was injected subcutaneously into mice. We examined the effect of MUC1 on ALI/ARDS in mice by detecting the expression of inflammatory factors and oxidative stress molecules in mouse lung tissue, bronchoalveolar lavage fluid (BALF) and serum. Overexpression of MUC1 effectively ameliorated LPS-induced damage to BEAS-2B cells. Results of H&E staining indicate that LPS successfully induced ALI/ARDS in mice and MUC1 attenuated lung injury. MUC1 also reduced the expression of inflammatory factors (IL-1β, TNF-α, IL-6 and IL-8) and oxidative stress levels in mice. In addition, LPS results in an increase in the activity of the TLR4/NF-κB signaling pathway in mice, whereas MUC1 decreased the expression of the TLR4/NF-κB signaling pathway. MUC1 inhibited the activity of TLR4/NF-κB signaling pathway and reduced the level of inflammation and oxidative stress in lung tissue of ALI mice.

Exosomal microRNA-98-5p from hypoxic bone marrow mesenchymal stem cells inhibits myocardial ischemia-reperfusion injury by reducing TLR4 and activating the PI3K/Akt signaling pathway

OBJECTIVE

MicroRNAs (miRNAs) are essential biomarkers during development of human diseases. We aimed to explore the role of hypoxia-induced bone marrow mesenchymal stem cells (BMSCs)-derived exosomal miR-98-5p in myocardial ischemia-reperfusion injury (MI/RI).

METHODS

BMSCs were isolated, cultured, stimulated by hypoxia and transfected with adenovirus expressing miR-98-5p. The exosomes were extracted from BMSCs and named as BMSC-exos. The rat MI/RI models were established by ligation of left anterior descending artery and were respectively injected. Then, hemodynamic indices, myocardial enzymes, oxidative stress factors, inflammatory factors, macrophage infiltration and infarct size in these rats were determined. Expression of miR-98-5p, toll-like receptor 4 (TLR4) and the phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt) signaling pathway-related proteins was assessed. The target relation between miR-98-5p and TLR4 was confirmed by bioinformatic method and dual luciferase report gene assay.

RESULTS

MiR-98-5p was downregulated, TLR4 was upregulated and the PI3K/Akt signaling pathway was inactivated in MI/RI rat myocardial tissues. Exosomal miR-98-5p from hypoxic BMSCs promoted cardiac function and suppressed myocardial enzyme levels, oxidative stress, inflammation response, macrophage infiltration and infarct size in I/R myocardial tissues. Moreover, TRL4 was targeted by miR-98-5p and miR-98-5p activated PI3K/Akt signaling pathway.

CONCLUSION

Hypoxia-induced BMSC-exos elevated miR-98-5p to protect against MI/RI. This study may be helpful for treatment of MI/RI.

Obesity and Pancreatic Cancer: Insight into Mechanisms

Simple Summary

Obesity is recognized as a chronic progressive disease and risk factor for many human diseases. The high and increasing number of obese people may underlie the expected increase in pancreatic cancer cases in the United States. There are several pathways discussed that link obesity with pancreatic cancer. Adipose tissue and adipose tissue-released factors may thereby play an important role. This review discusses selected mechanisms that may accelerate pancreatic cancer development in obesity.

Abstract

The prevalence of obesity in adults and children has dramatically increased over the past decades. Obesity has been declared a chronic progressive disease and is a risk factor for a number of metabolic, inflammatory, and neoplastic diseases. There is clear epidemiologic and preclinical evidence that obesity is a risk factor for pancreatic cancer. Among various potential mechanisms linking obesity with pancreatic cancer, the adipose tissue and obesity-associated adipose tissue inflammation play a central role. The current review discusses selected topics and mechanisms that attracted recent interest and that may underlie the promoting effects of obesity in pancreatic cancer. These topics include the impact of obesity on KRAS activity, the role of visceral adipose tissue, intrapancreatic fat, adipose tissue inflammation, and adipokines on pancreatic cancer development. Current research on lipocalin-2, fibroblast growth factor 21, and Wnt5a is discussed. Furthermore, the significance of obesity-associated insulin resistance with hyperinsulinemia and obesity-induced gut dysbiosis with metabolic endotoxemia is reviewed. Given the central role that is occupied by the adipose tissue in obesity-promoted pancreatic cancer development, preventive and interceptive strategies should be aimed at attenuating obesity-associated adipose tissue inflammation and/or at targeting specific molecules that mechanistically link adipose tissue with pancreatic cancer in obese patients.

Blocking TLR4-NF-κB pathway protects mouse islets from the combinatorial impact of high fat and fetuin-A mediated dysfunction and restores ability for insulin secretion

Lipid mediated pancreatic β-cell dysfunction during Type 2 diabetes is known to be regulated by activation of TLR4 (Toll Like Receptor 4) and NF-κB (Nuclear factor kappa B). Recently we have reported that MIN6 cells (mouse insulinoma cells) secrete fetuin-A on stimulation by palmitate that aggravates β-cell dysfunction, but the mechanism involved in-vivo has not been demonstrated and thus remained unclear. Here we attempted to dissect the role of palmitate and fetuin-A on insulin secretion using high fat diet (HFD) fed mice model. HFD islets showed curtailed insulin secretion after 20 weeks of treatment with activated TLR4-NF-κB pathway. Further treatment of islets with palmitate raised fetuin-A expression by ~2.8 folds and cut down insulin secretion by ~1.4 folds. However, blocking the activity of TLR4, fetuin-A and NF-κB using specific inhibitors or siRNAs not only restored insulin secretion by ~2 folds in standard diet fed mice islets and MIN6 cells but also evoke insulin secretory ability by ~2.3 folds in HFD islets. Altogether this study demonstrated that blocking TLR4, fetuin-A and NF-κB protect pancreatic β-cells from the negative effects of free fatty acid and fetuin-A and restore insulin secretion.

Body mass index-associated molecular characteristics involved in tumor immune and metabolic pathways

Background

Overweight or obesity has been evidenced as an important risk factor involved in the incidence, mortality, and therapy response of multiple malignancies. However, the differences between healthy and obesity tumor patients at the molecular and multi-omics levels remain unclear.

Methods

Our study performed a comprehensive and multidimensional analysis in fourteen tumor types of The Cancer Genome Atlas (TCGA) and found body mass index (BMI)-related genes in multiple tumor types. Furthermore, we compared composite expression between normal, overweight, and obese patients of each immune cell subpopulation and metabolism gene subset. Statistical significance was calculated via the Kruskal-Wallis rank-sum test.

Results

Our analysis revealed that BMI-related genes are enriched in multiple tumor-related biological pathways involved in intracellular signaling, immune response, and metabolism. We also found the different relationships between BMI and different immune cell infiltration and metabolic pathway activity. Importantly, we found that many clinically actionable genes were BMI-affect genes.

Conclusion

Overall, our data indicated that BMI-associated molecular characteristics involved in tumor immune and metabolic pathways, which may highlight the clinical importance of considering BMI-associated molecular signatures in cancer precision medicine.

In silico prediction and validation of potential therapeutic genes in pancreatic β-cells associated with type 2 diabetes

Diabetes mellitus is becoming a major health burden worldwide. Pancreatic β-cell death is a characteristic of type 2 diabetes (T2D), but the underlying mechanisms of pancreatic β-cell death remain unknown. Therefore, the aim of the present study was to identify potential targets in the pancreatic islet of T2D. The GSE20966 dataset was obtained from the Gene Expression Omnibus (GEO) database, and differentially expressed genes (DEGs) were identified by using the GEO2R tool. The Gene Ontology terms and Kyoto Encyclopedia of Genes and Genomes Pathway enrichment analysis of DEGs were further assessed using the Database for Annotation, Visualization and Integrated Discovery. Furthermore, protein-protein interaction (PPI) networks were constructed for the up- and downregulated genes using STRING databases and were then visualized with Cytoscape. The body weight, fasting blood glucose (FBG), pancreatic index and biochemistry parameters were measured in db/db mice. Moreover, the morphology of the pancreas was detected by hematoxylin and eosin staining, and hub genes were assessed using reverse transcription-quantitative PCR (RT-qPCR) and western blot analysis. In total, 570 DEGs were screened, including 376 upregulated and 194 downregulated genes, which were associated with 'complement activation, classical pathway', 'proteolysis', 'complement activation' and 'pancreatic secretion pathway'. It was found that the body weight, FBG, alanine aminotransferase, aspartate aminotransferase, total cholesterol, triglycerides, blood urea nitrogen, creatinine, fasting serum insulin, glucagon and low-density lipoprotein cholesterol levels were significantly higher in db/db mice, while high-density lipoprotein cholesterol levels and the pancreatic index were significantly decreased. Furthermore, albumin, interleukin-8, CD44, C-C motif chemokine ligand 2, hepatocyte growth factor, cystic fibrosis transmembrane conductance regulator, histone cluster 1 H2B family member n, mitogen-activated protein kinase 11 and neurotrophic receptor tyrosine kinase 2 were identified as hub genes in PPI network. RT-qPCR and western blotting results demonstrated the same expression trend in hub genes as found by the bioinformatics analysis. Therefore, the present study identified a series of hub genes involved in the progression of pancreatic β-cell, which may help to develop effective therapeutic strategy for T2D.

Pancreatic Macrophages: Critical Players in Obesity-Promoted Pancreatic Cancer

Obesity is a known risk factor for the development of pancreatic cancer, one of the deadliest types of malignancies. In recent years it has become clear that the pancreatic microenvironment is critically involved and a contributing factor in accelerating pancreatic neoplasia. In this context obesity-associated chronic inflammation plays an important role. Among several immune cells, macrophages have been shown to contribute to obesity-induced tissue inflammation. This review article summarizes the current knowledge about the role of pancreatic macrophages in early pancreatic cancer development. It describes the heterogenous origin and mixture of pancreatic macrophages, their role in pancreatic endocrine and exocrine pathology, and the impact of obesity on islet and stromal macrophages. A model is postulated, by which during obesity monocytes are recruited into the pancreas, where they are polarized into pro-inflammatory macrophages that drive early pancreatic neoplasia. This occurs in the presence of local inflammatory, metabolic, and endocrine signals. A stronger appreciation and more detailed knowledge about the role of macrophages in early pancreatic cancer development will lead to innovative preventive or interceptive strategies.